To ensure the safety of underground structures and surrounding environment of foundation pits, it is necessary to adopt protective measures such as support and reinforcement on the side wall and surrounding of foundation pits. The current support system for foundation pits generally includes an enclosing pile arranged around the edge of a foundation pit, a purlin arranged inside an enclosing pile of a foundation pit, and an inner support of a foundation pit arranged between the purlins. The inner support of a foundation pit usually includes a structural steel inner support beam supported by a prestress-pressing member arranged between the purlins, and the structural steel inner support beam pre-stresses on the prestress-pressing member through a hydraulic jack to support purlins on the opposite sides. Therefore the support for a foundation pit is formed to ensure the support strength of the support system for a foundation pit.
At present, end portions of structural steel inner support beams in the inner support system for foundation pits directly abut on the inner side of purlins, or through prestress-pressing members or through triangular members. The current inner support for foundation pits is a plane support structure with poor structural stability, therefore being not conducive to ensuring the support strength of the support system for foundation pits.
On the other hand, although structural steel inner support beams can support foundation pits, the present structural steel inner support beams in foundation pits are independent of each other, thereby affecting the overall stability of inner support of foundation pits, and further affecting the stability of inner support of foundation pits for support of foundation pits. Further, in order to improve the overall stability of inner support of foundation pits, the inventor arranges a tie beam between the adjacent structural steel inner support beams, wherein the tie beam and structural steel inner support beams are fixedly connected by bolts or welding. It seems to improve the overall stability of inner support of foundation pits, in the actual application process, however, it is found that the connecting beam is susceptible to shear failure. The connection between structural steel inner support beams cannot be formed by the tie beam and the overall stability of inner support of foundation pits cannot be improved.